基于CR理论的大柔性太阳能无人机非线性配平及飞行载荷分析
CR Approach of Nonlinear Trim and Flight Load Analysis of Very Flexible Solar Powered UAV

大柔性太阳能无人机在气动载荷的作用下产生较大的弹性变形,基于刚性或线弹性假设的结构模型已然不能满足这类飞机配平与飞行载荷分析的精度要求。基于co-rotational(CR)理论建立了大柔性飞机结构模型,并耦合片条气动力模型,提出了一种可以考虑几何非线性效应的大柔性飞机非线性配平及飞行载荷分析的方法。以类"太阳神"布局太阳能无人机为例,采用该方法对其不同有效载荷下的纵向配平及飞行载荷特性进行了较为深入的研究。研究结果表明:有效载荷较大时,采用线弹性假设的结构模型解得的配平误差可达50%以上,对翼尖位移的预测误差可达25%以上;该方法能够较合理地预测大柔性无人机的配平及飞行载荷特性,满足大柔性太阳能无人机结构设计对飞行载荷分析的工程精度要求。
A very flexible solar powered UAV under aerodynamic load undergoes large deformation; thus it is impossible to obtain its precise nonlinear trimming and flight load characteristics with the structural models that have rigid or linear assumptions. Therefore, combining the co-rotational theory with the aerodynamic strip theory, we develop an analysis algorithm which can deal with the geometrically nonlinear trimming and flight load characteristics of the very flexible solar-powered UAV. Taking a UAV with the layout similar to Helios for example, we explore the nonlinear trimming and flight load characteristics of the UAV under different payloads. The exploration results, given in Fig.5 through 12, and their analysis show preliminarily that: when applying the linear structural model to a large payload region, the trimming error of the UAV reaches 50% and the forecast error of its wingtip displacement reaches 25%. Our analysis algorithm can forecast the reasonable results on the very flexible solar-powered UAV and satisfy the precision requirements for the very flexible solar-powered UAV design in engineering